Expression of ICAM-1 and HLA class II in acute cellular and vascular rejection of human kidney allografts.

We studied the relationship between ICAM-1 and class II expression on graft tubular cells and the relationship with graft inflammation in 50 kidney transplants monitored with serial aspiration biopsies after transplantation. Of the 50 grafts, 26 had an acute rejection 17 +/- 10 days after transplantation, 5 also had acute vascular rejection (AVR) and 24 had no rejection. The initial post-transplant ICAM-1 and class II expression was low in all grafts. All 21 grafts with acute cellular rejection (ACR) displayed ICAM-1 induction, with a peak at the beginning of acute blastogenic rejection and declining over 20 days to prerejection levels. Class II expression reached a peak later and also declined later to prerejection levels. In the grafts with irreversible AVR both ICAM-1 and class II expression remained elevated. The 24 grafts with no rejection displayed no ICAM-1 or class II induction on tubular cells during the follow-up. The differences between ICAM-1 and classs II expression in biopsies with rejection and with no rejection were statistically significant. The results demonstrate that ICAM-1 was induced early during ACR on the graft tubular cells and that it disappeared rapidly in reversible rejections. The induction of class II antigens was slightly slower but quantitatively greater. In the irreversible rejections with a combination of ACR and AVR both ICAM-1 and class II expression remained elevated.